Air-gap-insulated exhaust manifold

Abstract

The present invention relates to an air-gap-insulated exhaust manifold ( 1 ) of an internal combustion engine, in particular in a motor vehicle, having a collecting line ( 2 ) that extends in a longitudinal direction ( 3 ), an outlet opening ( 4 ) oriented in the longitudinal direction ( 3 ), multiple inlet openings ( 5 ) oriented across the longitudinal direction ( 3 ) and a flange ( 6 ) that extends in the longitudinal direction ( 3 ) and includes the inlet openings ( 5 ), wherein an inside pipe ( 11 ) is situated in an outside pipe ( 10 ), forming an air-gap insulation, and whereby a gas-carrying outside pipe section ( 13 ) is provided in the area of at least one of the inlet openings ( 5 ) and leads from the respective inlet opening ( 5 ) to an assigned inside pipe inlet ( 14 ) which is at a distance from the flange ( 6 ). The inside pipe ( 11 ) is attached to the outside pipe ( 10 ) only in an attachment area ( 15 ).

1. An air-gap-insulated exhaust manifold of an internal combustion engine, in particular in a motor vehicle,
 comprising a collecting line ( 2 ) extending in a longitudinal direction ( 3 ), an outlet opening ( 4 ) oriented in the longitudinal direction ( 3 ), multiple inlet openings ( 5 ) oriented along the longitudinal direction ( 3 ) and a flange ( 6 ) extending in the longitudinal direction ( 3 ) and including the inlet openings ( 5 ), 
 wherein an inside pipe ( 11 ) is disposed in an outside pipe ( 10 ), forming air-gap insulation ( 12 ), 
 wherein a gas-carrying outside pipe section ( 13 ) is provided in the area of at least one of the inlet openings ( 5 ), leading from the respective inlet opening ( 5 ) to a respective inside pipe inlet ( 14 ) at a distance from the flange ( 6 ), 
 characterized in that 
 the inside pipe ( 11 ) is mounted on the outside pipe ( 10 ) exclusively in one attachment area ( 15 ) which is arranged with respect to the longitudinal direction ( 3 ) approximately centrally between the outlet opening ( 4 ) and the inlet opening ( 5 ) which is at the greatest distance from the outlet opening ( 4 ), 
 the inside pipe ( 11 ) is arranged movably at least in the longitudinal direction ( 3 ) in relation to the outside pipe ( 10 ) outside of the attachment area ( 15 ). 
 
   
   
     2. The exhaust manifold according to  claim 1 ,
 characterized in that 
 a gas-carrying outside pipe section ( 13 ) is provided in the area of the inlet openings ( 5 ) disposed outside of the attachment area ( 15 ). 
 
   
   
     3. The exhaust manifold according to  claim 1 ,
 characterized in that 
 the inside pipe ( 11 ) is movably mounted via a sliding seat ( 16 ) in the outside pipe ( 10 ) in the area of at least one inlet opening ( 5 ) disposed outside of the attachment area ( 15 ). 
 
   
   
     4. The exhaust manifold according to  claim 1 ,
 characterized in that 
 the collecting line ( 2 ) forms an inlet funnel ( 8 ) for a catalyst ( 9 ), wherein the outlet opening ( 4 ) is disposed at the outlet end of the inlet funnel ( 8 ). 
 
   
   
     5. The exhaust manifold according to  claim 1 ,
 characterized in that 
 the inside pipe ( 11 ) is positioned on the outside pipe ( 10 ) by means of locally limited spacer elements ( 17 ) which are stamped on the inside pipe ( 11 ) and/or on the outside pipe ( 10 ) and which allow displacement between the inside pipe ( 11 ) and the outside pipe ( 10 ) in the longitudinal direction ( 3 ). 
 
   
   
     6. The exhaust manifold according to  claim 1 ,
 characterized in that 
 the inside pipe ( 11 ) has a smaller wall thickness, in particular at least 50% smaller than the wall thickness of the outside pipe ( 10 ). 
 
   
   
     7. The exhaust manifold according to  claim 1 ,
 characterized in that 
 at least one bearing mat is provided in the air-gap insulation ( 12 ) and is limited at least locally. 
 
   
   
     8. The exhaust manifold according to  claim 1 ,
 characterized in that 
 the attachment area ( 15 ) is formed only in the area of the inlet opening ( 5 ) which is disposed approximately centrally with respect to the longitudinal direction ( 3 ) between the outlet opening ( 4 ) and the inlet opening ( 5 ) at the greatest distance from the outlet opening ( 4 ). 
 
   
   
     9. The exhaust manifold according to  claim 8 ,
 characterized in that 
 the inside pipe ( 11 ) extends up to or into the flange ( 6 ) in the attachment area ( 15 ) and is attached there to the outside pipe ( 10 ), the outside pipe ( 10 ) being attached to the flange ( 6 ) in the attachment area ( 15 ). 
 
   
   
     10. The exhaust manifold according to  claim 1 ,
 characterized in that 
 in the area of at least one inlet opening ( 5 ) which is disposed outside of the attachment area ( 15 ), the inside pipe ( 11 ) includes an inside pipe inlet ( 14 ) which is oriented essentially parallel to the respective inlet opening ( 5 ) and is arranged to be free-standing in front of an outside pipe section ( 13 ) which leads to the respective inlet opening ( 5 ). 
 
   
   
     11. The exhaust manifold according to  claim 10 ,
 characterized in that 
 the inside pipe ( 11 ) and the outside pipe ( 10 ) are mutually coordinated so that the inside pipe inlet ( 14 ) is aligned approximately centrally with the respective inlet opening ( 5 ) at operating temperature, and in a cold state, said inside pipe ( 11 ) is eccentrically offset in relation to the respective inlet opening ( 5 ) with respect to the longitudinal direction ( 3 ). 
 
   
   
     12. The exhaust manifold according to  claim 1 ,
 characterized in that 
 the inside pipe ( 11 ) formed of one piece. 
 
   
   
     13. The exhaust manifold according to  claim 12 ,
 characterized in that 
 the inside pipe ( 11 ) is produced by internal high-pressure forming or is assembled from two half shells.